This application is a 35 USC 371 application of PCT/DE 00/03043 filed on Sep. 5, 2000.
1. Field of the Invention
The invention relates to an air filter and particularly to such a filter for filtering the intake air for internal combustion engines of motor vehicles.
2. Description of the Prior Art
Air filters for filtering the intake air for internal combustion engines which are known for example from Bosch xe2x80x9cKraftfahrtechnisches Taschenbuchxe2x80x9d [Automotive Handbook] 1998, p. 422 ff., to keep the dust contained in the intake air away from the engine and prevent a premature wear on the engine. The filter matte, which retains the dust and must be replaced at maintenance intervals, is matched to the engine in order to optimize performance, fuel consumption, and damping of the intake noise. A number of outlet bores are provided in the bottom of the filter housing in order to discharge condensation water that forms in the filter housing.
U.S. Pat. No. 5,507,858 has disclosed a device for separating the gaseous and fluid liquid phases of a gas/oil mixture in a pipeline, which has a housing with an inlet and an outlet inserted into the pipeline, which housing contains a water separator. The water separator, which is comprised of a perforated plate, is aligned in oblique fashion, i.e. at an acute angle to the axes of the inlet and outlet, and divides the housing into a housing section connected to the inlet and a housing section connected to the outlet. A liquid outlet is provided in the latter housing section so that the liquid being separated in the water separator can be discharged from the housing.
The air filter according to the invention, has the advantage that on the one hand, water particles contained in the intake air are precipitated in the water separator and adhere to the bottom of the filter housing and on the other hand, the water collecting at the bottom of the filter housing is also reliably discharged via the water outlet during operation of the engine and does not collect in the dead flow spaces of the filter housing. As a result, the filter matte in the filter housing becomes less moist and cannot become fully laden with moisture so that secondary malfunctions on the clean air side due to water passing through the fully laden filter matte can be prevented.
According to an advantageous embodiment of the invention, the necessary water level in the water outlet is realized by virtue of the fact that an outlet opening in the filter housing is connected to an outlet tube in the course of which an annular loop or a meandering bow is embodied after the fashion of a water seal. In this connection, the outlet tube is preferably embodied as a hose.
According to a preferred embodiment of the invention, the means for producing the water level have an outlet tube which leads from an outlet opening in the filter housing and is filled with absorbent material. A similar absorption effect is also produced by means of a high surface roughness of the inner tube wall of the outlet tube or through the provision of a constriction in the course of the outlet tube.
All the above-mentioned embodiments have the advantage that less space is required underneath the filter housing to accommodate the outlet tube than is the case with the embodiment of a loop or bow in the outlet tube. In addition, there is not a constant water seal in the outlet tube which can freeze in winter, but instead, the water level is only built up to the required level during operation of the engine through the mechanism of absorbency. Trials have shown that an improved water separation is produced, independent of this fact.